The end of the 14th century. Parents send the eldest son Jan to study in Hamburg, and the youngest - Klaus - to the monastery. No sooner had the children moved away from their homes, as on Klaus'es eyes the robbers kill their parents and burn the house. Only thanks to the loyal monk Wigbold Klaus managed to survive the shock. A few years later Klaus Störtebeker finds his brother Jan and his long-time friend Elizabeth Pren in Hamburg. From her, he learns that she is expected to marry Simon von Wallenrod, whose father Klaus suspects of killing his parents. But the Pranks and the Wallenrods are rich and respected people, and Klaus is a poor man. And now he becomes a pirate...